Einelektronen‐Redox‐Reaktionen von Octamethyl[4]radialen: Nachweis der Alternanz geradzahliger Radialene

Abstract

One‐Electron Redox Reactions of Octamethyl[4]radialene: Proof of the Alternancy of Even‐Membered RadialenesThe photoelectron spectrum of octamethyl[4]radialene ( = tetrakis(dimethylmethylidene)cyclobutane) yields the rather low first vertical ionization of only 7.30 eV and, therefore, the molecule can be oxidized by AlCl3/CH2Cl2 to its radical cation. The ESR and ENDOR signal patterns recorded are almost identical with those of the radical anion, generated in a [2.2.2]cryptand THF solution by reduction at a potassium metal mirror. Their near congruency is in accord with the alternant π molecular properties of even‐membered radialenes as predicted by HMO theory, and larger changes of the D2d structure of C8(CH3)8 during the redox reactions are presumably hindered by the steric overcrowding in persubstituted [4]radialenes.